The invention relates to a laser-marked polymer workpiece, a method for its production, and its use.
Plastic panes for motor vehicles are typically produced in the multi-component injection molding method. Customarily, a darkly colored, usually black, opaque component is applied to a transparent component in the edge region of such a pane. In the region of the opaque component, the pane can be bonded, for example, glued, to the motor vehicle body in a manner not visible to the observer.
By means of a mark or inscription, for example, a manufacturer's code, approval mark, a production date, or optical effects can be applied to the pane. Different methods are known for marking plastic panes. With injection molding of the pane, the mark can be introduced as a negative or positive relief in the surface of the pane. However, image sharpness, contrast, minimum font size, and level of detail are limited. In addition, because of the relief, marginal coating distribution problems can occur at the time of lacquer coating of the pane.
Alternatively, a mark can be engraved or milled into the pane as a relief after injection molding. Here, as well, at the time of lacquer coating of the pane after marking, coating distribution problems can occur. Application of the relief after lacquer coating of the pane damages the lacquer layer.
Methods for laser marking of plastic panes are also known. In that case, the marking is based on a darkening of a region of the surface of the pane as a result of laser irradiation. Here, the mark is also not protected against mechanical and chemical damage as well as UV radiation. With lacquer coating of the pane after laser marking, coating distribution problems can occur. Application of the mark after lacquer coating of the pane damages the lacquer layer. The darkening can be produced by other known methods even in the interior of a plastic pane. Since the darkened mark is not discernible against the background of the opaque component in the edge region of the pane, the mark must be applied in the transparent visual field of the pane, where it can have a disturbing effect.
Methods, with which a laser mark can be introduced into polymer workpieces in the form of a darkening, are, for example, known from DE19944372A1, WO2010019194A1, DE19732306A1, and WO2010054077A2.
Also known are methods of laser marking in which laser sensitive materials specially introduced into the workpiece are used, for example, from DE102009028937A1 and WO2010023102A1. However, the production of the workpieces is rendered more difficult by the necessity of the laser sensitive materials.